Dates June 26-July 16, 2005. Type of participants; undergraduate students. Goals and Topics: A three-week intensive Summer Institute in mathematical biology is proposed for 30-40 undergraduate students and 20 undergraduate faculty. We propose 3 innovative, contemporary courses meet daily on topics of central importance in mathematical biology, as well as a fourth course (in the Undergraduate Faculty Program) focused on the biological knowledge necessary for mathematics faculty preparing to offer mathematics courses for math biology students. The instructors for the Summer Institute courses are chosen each year from among eminent research mathematicians noted as among the best expositors in their field. In 2005, the USS lecturers will be Lisette de Pillis (Harvey Mudd College) "Cancer Modeling with Optimal Control," Fred Adler (University of Utah) "Dynamics, Diseases, and Diversity," and Elizabeth Allman (University of Southern Maine) and John Rhodes (Bates College). Allman and Rhodes will jointly offer one course "The Mathematics of Phylogenetic Trees." In addition, the Undergraduate Faculty Program course will be offered by John Tyson (Virginia Polytechnic University) "An Introduction to Molecular Cell Biology for Mathematicians." In addition, considerable interaction is planned with a Graduate Summer School and Research Program in Mathematical Biology occurring simultaneously in the same location, as well as a program for secondary and middle school mathematics teachers. Participants will also have access to the presentations of 2 Clay Mathematics Institute Senior Scholars-in-Residence: Simon Levin of Princeton University and Charles Peskin of Courant Institute, New York University.